Field of the Invention
Aspects of the present invention relate generally to a processor and an apparatus capable of reducing image flicker and a related method and, more particularly, to a processor and an apparatus capable of reducing image flicker by performing a mapping between utility frequencies and telecom operators and a related method.
Description of the Related Art
Image capture devices, such as digital video cameras or digital still photo cameras, are used in different applications and environments. An image capture device should be capable of producing high-quality imagery under a variety of lighting conditions. For example, image capture devices should be capable of operating effectively in environments illuminated by natural light, such as outdoor environments, as well as in environments illuminated by incandescent or fluorescent lights, such as indoor environments.
In an indoor environment, however, fluctuations in the intensity of indoor lighting can degrade the quality of the captured image. The fluctuations are a function of the alternating current (AC) electrical power frequency of the indoor lighting source, which is the so-called utility frequency. A solid state image capture device, such as a complementary metal oxide semiconductor (CMOS) device, includes an array of image sensors that do not instantaneously capture all of the image information used to record a frame. Consequently, fluctuations in light intensity during image capture cause portions of an image frame to exhibit different intensity levels, resulting in visible bands in the image. This banding phenomenon is commonly referred to as flicker. Variations in the AC power frequency of indoor lighting or utility frequency exist throughout the world. Some countries use 60 Hertz (Hz) power, for example, while other countries use 50 Hz power. A 60 Hz illumination source causes banding at 120 Hz, while a 50 Hz illumination source causes banding at 100 Hz.
Flicker may be eliminated by setting an exposure time of the image capture device to an integer multiple of the period of the illumination source or a utility frequency. The exposure time may refer to the time limit for the sensor array to capture light for each frame. In other words, to reduce the image flicker, a current utility frequency f is detected first, and an image sensor exposure time can be adjusted to be a multiple of 1/2f.
Most mobile apparatuses use an image-based detection algorithm to detect the current utility frequency. However, most people only leave their own country 1 or 2 times a year. A lot of CPU computing power of the mobile apparatus may be wasted on detecting the current utility frequency by using the image-based detection algorithm even when the user is not traveling to a new region. Thus, there is a need to develop an apparatus and a related method for detecting utility frequency and reducing image flicker.